This learning resource is available in interactive and printable formats. The interactive worksheet can be played online and assigned to students. The Printable PDF version can be downloaded and printed for completion by hand.
This reading passage, 'The Mass of a Proton,' introduces middle school students to one of the smallest yet most important particles in an atom—the proton. With a mass of 1.67 × 10⁻²⁷ kilograms, the proton plays a key role in determining the atomic mass and identity of an element. The passage explains that protons are located in the nucleus of atoms, carry a positive charge, and—along with neutrons—account for nearly all of an atom’s mass. Aligned with NGSS standard MS-PS1-1, which focuses on the structure and properties of matter, the passage also supports Common Core standards like RI.6.1 and RI.6.4. The language is clear and accessible, making it ideal for middle grade readers. Includes 8 multiple choice questions, vocabulary practice, and a fun fact to boost engagement. Perfect for cross-curricular instruction that builds science and literacy skills.
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"Atom (PSF)" by Pearson Scott Foresman / Wikimedia Commons.
Everything around you is made of atoms—tiny building blocks that make up all matter. But what are atoms made of? At the center of every atom is the nucleus, and inside the nucleus are particles called protons and neutrons. This passage focuses on protons, and one important property they have: mass.
A proton is a positively charged particle found in the nucleus of an atom. Even though protons are very small, they still have mass. The mass of a single proton is about 1.67 × 10⁻²⁷ kilograms. That’s a very tiny amount, but it's incredibly important!
In fact, most of the mass of an atom comes from the protons and neutrons in its nucleus. Electrons, which are found outside the nucleus, have almost no mass in comparison. That’s why the number of protons and neutrons determines the atomic mass of an element.
The number of protons in an atom is also called its atomic number, and it tells us what element it is. For example, hydrogen has one proton, while carbon has six.
Even though protons are tiny, they play a big role in the structure of matter. Their mass helps determine the weight of atoms, molecules, and everything we see around us.
Fun Fact: Even though protons are incredibly small, if you lined up a billion billion protons side by side, they would stretch just 1 meter!
What is the main idea of the passage?
Protons have no massThe role of electrons in atomsThe mass and importance of protons in atomsHow atoms turn into molecules
Where are protons found in an atom?
In the electron cloudOutside the atomIn the nucleusIn the outer shell